Stocks & broths
glace de poisson
glace de poisson · A deeply reduced white fish stock cooked to a syrupy nappe consistency — the fish counterpart to demi-glace. It is the essential finishing element and flavor base in classical French and modern restaurant seafood cookery.
The formula
2 L water : 1 kg raw bones → reduce 85–90% to nappe
Scale by weight of raw fish bones. Starting ratio: 1 kg raw white fish bones + 300 g mirepoix + 2 L cold water → simmer 20 min → strain → add 150 mL dry white wine → reduce to ~200–250 mL glaze. Yield: ~200 g. Freeze in 20 g ice cube trays.
Identity
- Made from raw, rinsed white fish bones — never oily or dark-fleshed fish
- Reduced to nappe: coats a spoon thickly, flows in a slow sheet when tilted
- Never boiled hard during initial simmer — gentle 80–85 °C surface keeps stock clear
- Strained through fine chinois with no pressure on solids
- Seasoned only at service, never during reduction
Ingredients
| Base | raw white fish bones and trimmings (sole, turbot, cod, haddock) | Rinsed thoroughly in cold water until runs clear. Bones from lean white fish only. Avoid oily fish (salmon, mackerel, herring) — their fat oxidizes and turns bitter. |
| Liquid | cold water | Covers bones by 2–3 cm. Starting cold extracts gently; boiling water clouds the stock. May substitute 1:1 with prepared fish fumet for extra intensity. |
| Aromatics | mirepoix: onion, carrot, celery (ratio 2:1:1) | 300 g total per 1 kg bones. Optionally bound with 30–50 g tomato purée for classic matignon. |
| Acid | dry white wine | 150 mL per 1 kg bones. Added after straining. Essential for brightness and mineral extraction from bones. |
| Seasoning | bouquet garni: parsley stems, thyme, bay leaf | Added after initial skimming. Removed before final reduction. |
| Flavor | cognac or armagnac (optional) | 1 tablespoon brandy added after straining deepens flavor. Flambé before adding wine for restaurant practice. |
Method
- 1Rinse fish bones and trimmings in several changes of cold water until water runs clear.Blood and viscera cause bitterness and cloudiness. Rinsing is non-negotiable for a clean, sweet stock.
- 2Combine bones, cold water, and mirepoix in a stockpot. Bring to a gentle simmer over medium heat.Slow heating extracts gelatin and flavor compounds without agitating proteins into the liquid, keeping the stock clear.
- 3Skim the surface vigorously with a ladle every 2–3 minutes for the first 15 minutes of simmering.Impurities (scum) rise to the surface during protein coagulation. Skimming prevents reincorporation.
- 4Add bouquet garni, maintain gentle simmer (80–85 °C, not boiling), cook 20 minutes total from simmer.Twenty minutes is sufficient to extract gelatin without pulling bitter compounds from bones. Longer extraction degrades clarity and introduces off-notes.
- 5Strain through a fine chinois lined with damp cheesecloth, without pressing the solids.Pressing forces bitter compounds from vegetables into the liquid. Gravity straining alone yields clarity.
- 6Add white wine and any flambéed brandy. Reduce over medium-high heat until the liquid reaches nappe consistency — it coats a spoon thickly and sheets off slowly when tilted.Reduction concentrates flavor by 8–10×. Nappe consistency indicates the stock has the body of a light syrup, roughly 10–12 °Brix, or a boiling point elevation of 102–105 °C.
- 7Cool rapidly in an ice bath and portion into airtight containers or 20 g ice cube trays.Rapid cooling prevents bacterial growth. Pre-portioned frozen cubes add the glaze at service without additional reduction.
Techniques that matter
Reduction (concentration)
Each halving of volume approximately doubles concentration of flavor compounds. The glaze reaches ~10× the strength of the starting stock.
Ice-cube freezing
Restaurant standard. Pre-portioned frozen cubes add the glaze to sauces at the last moment without additional reduction at service.
Gentle simmer and skimming for clarity
Unlike meat stocks that may be clarified with egg whites, fish stock relies on slow extraction and careful skimming. Egg whites can introduce off-flavors in fish preparations.
Variations & derivatives
glace de crustacésFrance
Lobster, shrimp, or crab shells reduced and glazed. The same technique applied to shellfish — richer, sweeter, more briny. Essential for bisque and araignée sauce.
fond de poisson blancFrance
The un-reduced white fish stock itself, used as a base for sauces like vin blanc. The parent preparation before reduction.
bouillon de poissonFrance/Méditerranée
A lighter, herb-forward fish broth served as a soup. Glace de poisson is its concentrated essence.
Used in these dishes
Substitutions
- glace de poisson → light soy sauce + fish stock reduction — Umami-equivalent substitution for modern non-French kitchens. Use sparingly — soy adds color and salt profile not present in the original.changes result
- glace de poisson → dashi + white wine reduction — Japanese dashi has cleaner marine notes; combining with white wine reduction approximates acidity and concentration. Safe for neutral-flavor dishes.
- fresh fish stock → pre-made commercial fish stock paste — Dissolve 1 tbsp paste per 250 mL water. Convenient but lacks depth of proper homemade glaze. Add white wine and reduce further.
Troubleshooting
Stock is cloudy
Bones were not rinsed, water was boiled rapidly, or solids were pressed during straining. → Fish stock cannot be clarified with egg whites (introduces fishy off-flavor). Start over. Prevention is the only cure — slow simmer and no pressing are essential.
Glaze is bitter or tastes fishy/off
Oily fish bones used, bones cooked too long (over-extraction of guanine and histidine compounds), or stock reduced at too high a temperature. → Add 50 mL cold water and a pinch of sugar, re-strain, and reduce again carefully. If severely bitter, discard and begin with properly rinsed white fish bones.
Glaze doesn't reach nappe consistency
Insufficient reduction — most common with inadequate starting volume or evaporation pan too wide. → Use a narrow saucepan to minimize surface area. Reduce until a wooden spoon coated in glaze shows a thick, slow-moving film.